煤矸石取代粗集料的混凝土抗渗性和抗冻性研究

发布时间：2018-03-10 23:29

本文选题：煤矸石混凝土　切入点：力学性能　出处：《沈阳建筑大学》2015年硕士论文　论文类型：学位论文

【摘要】：煤矸石是煤炭工业产生的废物之一,每年都在产生大量的煤矸石、对环境有严重的污染。对煤矸石不进行合理的利用,将产生巨大的社会、经济和环境的损失。利用煤矸石生产集料来拌制水泥混凝土,可以大量减少土木工程中对天然集料的使用量,具有较好的经济效益和社会效益。本课题通过煤矸石作为粗集料取代碎石制备混凝土,采用单因素和优化设计试验方案,以混凝土抗压强度、抗渗性和抗冻性为考核指标,确定煤矸石取代碎石的合理掺量范围,研究了煤矸石的掺量、水胶比的大小、粉煤灰的掺量、外加剂的种类和掺量对混凝土抗渗性、抗冻性的影响规律,并于普通混凝土做出对比。研究结果表明:(1)通过煤矸石和普通碎石的基本物理性能的对比可知,煤矸石孔隙率较大,含水率较高,吸水性较强,含泥量较大;压碎指标较大;以煤矸石混凝土拌合物的工作性和力学性能为考核指标,确定煤矸石取代碎石的合理掺量范围在60%以内。(2)在基准配合比条件下,随着煤矸石取代碎石的量从0%增加到60%,混凝土的抗压强度、抗渗性、抗冻性有不同程度的降低,抗压28天强度从55.7MPa下降到40.8MPa,抗渗压力从1.3MPa下降到0.9MPa,冻融次数从300次以上下降到150次以下,煤矸石的最佳取代量在40%左右;水胶比从0.35增大到0.45,抗渗压力从1.3MPa下降到0.7MPa,冻融次数从300次下降到100次左右,确定满足C40混凝土的水胶比不大于0.4;粉煤灰作为矿物掺合料,当掺量在10%左右抗冻抗渗效果最好,抗渗压力可达1.2MPa,冻融循环可达300次,超过20%时,混凝土抗渗性、抗冻性有明显的下降趋势;选用聚羧酸减水剂和引气剂可以显著提高混凝土抗渗、抗冻性,聚羧酸减水剂和引气剂的掺量分别占胶凝材料约0.5%和0.02%时,抗渗和抗冻能力最强,均可达到1.1MPa和300次冻融循环;两种外加剂复合使用时,比单掺一种外加剂效果更好,抗渗和抗冻分别可达到1.3MPa和350次冻融循环。(3)掺入矿物掺合料和外加剂可以改善混凝土的孔结构,经冻融循环后,最可几孔径和总孔体积减小,孔结构劣化的速率明显减慢。300次冻融前后比较,掺入粉煤灰可使混凝土的总孔体积增大的百分比从12.6%下降到9.2%,其最佳掺量在胶凝材料的10%;复合使用聚羧酸减水剂和引气剂可使混凝土总孔体积增大的百分比从12.8%下降到5.7%,减水剂和引气剂的掺量分别为0.4%和0.02%时达到最佳。
[Abstract]:Coal gangue is one of the wastes produced by the coal industry. It produces a large amount of coal gangue every year, which causes serious pollution to the environment. If the coal gangue is not used reasonably, it will produce a huge society. Economic and environmental losses. The use of coal gangue to produce aggregate to mix cement concrete can greatly reduce the amount of natural aggregate used in civil engineering. In this paper, coal gangue is used as coarse aggregate instead of crushed stone to prepare concrete. Single factor and optimum design test scheme are adopted. The compressive strength, impermeability and frost resistance of concrete are taken as the assessment index. The reasonable dosage range of coal gangue instead of crushed stone is determined. The influence of coal gangue content, water / binder ratio, fly ash content, type and amount of admixture on the impermeability and frost resistance of concrete is studied. The research results show that the coal gangue has higher porosity, higher moisture content, stronger water absorption, larger mud content, larger crushing index, higher porosity, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water content, higher water. Taking the workability and mechanical properties of coal gangue concrete mixture as evaluation indexes, it is determined that the reasonable dosage range of coal gangue replacing crushed stone is less than 60% under the condition of standard mix ratio. As the amount of coal gangue replacing crushed stone increased from 0% to 60, the compressive strength, impermeability, and frost resistance of concrete decreased to varying degrees. The compressive strength decreased from 55.7 MPA to 40.8 MPA, the impermeability pressure decreased from 1.3 MPA to 0.9 MPA, the freeze-thaw times decreased from more than 300 times to less than 150 times, and the optimum substitution of coal gangue was about 40%. The water-binder ratio increased from 0.35 to 0.45, the impermeability pressure decreased from 1.3 MPA to 0.7 MPa, and the freeze-thaw times decreased from 300 times to about 100 times. The impervious pressure can reach 1.2 MPA, the freeze-thaw cycle can reach 300 times, when the concrete is more than 20, the impermeability and the frost resistance of the concrete have an obvious downward trend, and the use of polycarboxylic acid water reducer and air entraining agent can significantly improve the impermeability and frost resistance of concrete. When the content of polycarboxylic acid water reducer and air entraining agent is about 0.5% and 0.02, respectively, the impermeability and freezing resistance are the strongest, which can reach 1.1MPa and 300th freeze-thaw cycle respectively. When the two admixtures are combined, the effect is better than that of single admixture. The pore structure of concrete can be improved by adding mineral admixture and admixture, which can reach 1.3MPa and 350 freeze-thaw cycles, respectively. After freeze-thaw cycle, the pore size and total pore volume of concrete can be reduced. The rate of deterioration of pore structure was significantly decreased. 300 times before and after freezing and thawing, The percentage of the total pore volume of concrete decreased from 12.6% to 9.2 by adding fly ash, and the optimum content was 10% of the cementing material, and the percentage of the total pore volume of concrete increased from 12.8% to 12.8% by using polycarboxylic acid water reducer and air entraining agent. When the ratio of water reducer and air entraining agent is 0.4% and 0.02, respectively, the best results are obtained.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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